Magnetic iron alloy



Patented Jan. 5, 1937 2,006,920 I 'monnrro mow Armor Robert A. Chicago, l., assignor, by mesne assignments, to Indiana Steel Products Company, Chicago, 1th., a corporation of Indiana No Drawing. Se

Application April 20, 1936,

5 Car- (032. w -123) This invention relates to a magnetic iron alloy and more particularly to a quaternary alloy of nickel, beryllium, cobaltror columbium and iron, having permanent magnetic qualities and 5 also heat-resistant and corrosion resistant properties.

It has heretofore been known (Ruder Patent No. 1,947,274) to cast alloy permanent magnets consisting of nickel, aluminum and iron. It has 10 also been known to provide alloy steels of nickel, aluminum, cobalt and iron for use in permanent magnets. Other workers in the field have suggested adding up to 12% of beryllium to alloys. of nickel and iron. 1

15 I have found, however, that if a quaternary alloy of nickel, beryllium, cobalt or columbium, and iron is used, it is possible to obtain the same desirable magnetic properties with a much less content of cobalt and beryllium than has here- 29 tofore been found necessary where only ternary alloys have been employed. I have also-found that the quaternary alloy of my invention may be worked, as by hot rolling, whereas this was not possible in the case of the. ternary alloys pre- 5 viously used.

It is therefore an important object of this invention to provide a quaternary alloy consisting essentially of nickel, beryllium, cobalt or columbium. and iron, having permanent mag-.

3 netic properties and also good resistance to heat and corrosion.

Other and further important objects of this invention will. become apparent from the following description and appended claims.

The alloy of'my invention has the following general composition, percentages being expressed as percentages by weight:

Nickel 15 to 25% Beryllium -1 0.25 to 2% 40 Cobaltor columbium 1 to Low carbon iron; Balance the percentage of beryllium is 1%, then the cobalt, or columbium content should be between 3 and 5%.

sented by ailow carbon iron, such as an iron containing 0.45% carbon or less. A carbon content of 0.10% for the iron is eminently satis- 55 facto y.

. It is important that the iron'content be repre- Nickel 20% Beryllium 1% Cobalt 3to5% 10 Low carbon iron (0.10 carbon content) Balance An alloy of the foregoing analysis may be prepared by melting the alloying ingredients together in a suitable type of furnace, without necessitating any extreme care to prevent oxidation, as is the case where aluminum is used as one of the alloying ingredients. The molten alloy is then cast into suitable form and the casting is preferably subjected to a heat treatment.

A suitable type of heat treatment comprises raising the temperature of the cast material to 1600 F. and immediately quenching, followed by a soak at 750 to 850 F. and air quenching. The length of soak will depend upon the temperature employed, the higher the temperature the shorter the length of time required. For instance if a temperature of 750 F. is employed, a time of 15 minutes would be satisfactory, while at 850 C.,

, 5 minutes might be sufiicien The purpose of the heat treatment is to age the alloy. Since, however, the alloy has age hardening properties, these properties will be developed in time without the necessity of heat treatment. The purpose, therefore, of the heat treatment is merely to speed up the acquiring of the desired properties in the alloy. M

The cast alloy may be worked to size by hot rolling, or other forging operation. This working of the metal can be carried out either before or after the heat treatment operation. It is obviously of considerable advantage that the metal can be worked, since this eliminates the necessity of using more laborious and time consuming methods, such as grinding and the like.

The magnetic properties of a cast alloy of my invention will depend in part upon the size of the casting. As illustrative of the magnetic properties possessed by a quaternary alloy of the foregoing analysis, a bar of such alloy consisting of about 20% of nickel, 1% of beryllium, 3 to 5% cobalt and the balance low carbon iron, shows a coercive force varying from about 425 to 475 Gilberts per centimeter, and a residual varying from about 7000 to 8000 Gauss.

Although cobalt is the preferred ingredient of the two, columbium may be substituted in whole for the cobalt without greatly sacrificing the desired magnetic properties of the alloy.

I am aware that numerous details of the process may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention:

1. A quaternary alloy having as its essential ingredients the following analysis, percentages by weight being indicated:

Nickel 15 to 25% Beryllium 0.25to 2% Cobalt 1 to 10% Low carbon iron Balance 2. 'A magnetic iron alloy consisting essentially of about 20% nickel, 1% beryllium, 3 to 5% cobalt and the balance low carbon iron.

3. A magnetic iron alloy consisting essentially of about 20% nickel, 1% beryllium, 3 to 5% of cobalt, and the balance an iron containing less than 0.45% carbon.

4. A permanent magnet 01 a quaternary alloy consisting essentially of about 20% nickel, 1% beryllium, 3 to 5% cobalt and the balance an iron 0! about 0.10% carbon.

5. A quaternary alloy consisting essentially of nickel, cobalt, beryllium and low carbon iron, the nickel being present in an amount between 15 and 25%, the cobalt and beryllium being presentin amounts not over 12% and being in the ratio of between 3 and 5 parts of cobalt to l of beryllium.

ROBERT A. CURRY. 

